Mailman 3 June 2013 - Edu-sig

a short essay about programming
by kirby urner Dec. 9, 2022

Dec. 9, 2022

A common "error" (not too serious) that I see in beginning Python (and no doubt other languages, but Python is the one I'm teaching), is having a while condition that appears to put a lid on things, but then the flow all leaks away through break statements, such that the "front door" condition is never revisited. while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") What's messed up about the above code is you never really go back to the top in the case where you'd get to leave. Rather, you exit by the back door, through break. So in that case, wouldn't have been simpler and more elegant, even more "correct" (dare I say it) to have gone: while True: # no ifs ands or buts guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") break else: print("Nope, try again...") I see lots of heads nodding, and that could be the end of the matter, but then a next question arises: wouldn't this also be a more correct solution?: while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") continue # instead of break else: print("Nope, try again...") We're back to having a variable while condition, not a boolean constant, but this time we actually exit by means of it, thanks to continue or... while guess != secret: guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") else: print("Nope, try again...") ... thanks to no continue. This last one is getting a thumbs up, but then I'd pause here and say "continue" can be easier on the eyes. It's unambiguous where it takes you, in contrast to having to scan on down the gauntlet, looking for possibly other open doors. "What happens next" should not require scanning ahead too far. Help us not to get lost. Be a civic-minded coder. I'm thinking of a programming style that advises two things: (a) if you use a while condition that's variable, that's expected to change, then your goal should be to always exit because of that, i.e. that should be your only exit point. Even if some other criterion suggests exiting, you have the option to flip that "lid" at the top, to crack that front door, and bounce the ball out. (b) which is why 'continue' is your friend. You are showing the user where your 'break' statements are, except you don't use "break" statements, as you've given a non-constant condition, and your aim is to make that your ONLY exit point. In short: never use break to exit a while loop unless your condition is while True. Instead, always flip the condition and exit through the font door. However, as soon as I make that rule I can think of good reasons to break it. The other programmers in the room are shaking their heads. Won't we lose information, needed elsewhere in the program, if we "artificially" force a True condition to False. Aren't we, in effect, lying? That concern could be addressed. Keep all the info true, just treat the "lid condition" (it "keeps a lid on it") as a flag. Go ahead and remember the user's guess. allowed = 5 tries = 1 exit = False while not exit: # no other way out guess = int(input("Guess?: ") if guess == secret: print("You guessed it!") exit = True # instead of break continue print("Nope, try again...") tries += 1 if tries == allowed: print("You've maxed out") exit = True continue I think we all understand the main issue: writing reader-friendly code, and rules for doing so. There's something comforting about approaching a while loop and knowing its not a leaky sieve, riddled with back doors, maybe even an exit( ) time bomb. But in the recursion world we want a minimum of two exits usually: when another round is called for versus when we've "hit bottom". Can we have it both ways? Conclusions: Lets not be too hasty with rules of thumb and: Lets keep the reader in mind when writing code. Just because the interpreter knows to compute the flow unambiguously, doesn't mean all ways of writing it are equally reader-friendly. What may seem a gratuitous gesture, an unnecessary flourish, may actually promote reader comprehension of your code, and that should be a goal as much as satisfying the interpreter. Kirby

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Re: [Edu-sig] RurPLE-NG is nice
by Jurgis Pralgauskis April 6, 2014

April 6, 2014

Some updates: - separated Variables Watch and Output panes, to be seen simultaneusly - implemented Breakpoints :) - beta style Todo: - let enter arbitrary watch expressions http://ftp.akl.lt/users/jurgis/python/rurple-NG053.png http://ftp.akl.lt/users/jurgis/python/rurple-ng-dz0-SplitLogVars_and_Breakp… for windows one doesn't need to install python separately, just unzip and run :) http://ftp.akl.lt/users/jurgis/python/RURPLE-NG-0.53%20%5bindependent%20exe… ps.: RurPLE-NG uses py3 unicode_literals, with_statement, division, print_function so code is generally py3 compliant. when wxpy will work well with py3 it shouldn't be too hard to port fully... >> >> just wanted to mention, >> that http://dev.lshift.net/paul/rurple/ >> is a very nice and lightweit PLE. >> >> what I like most (compared to RurPLE) are: >> 1) variables watch list (if it had breakpoints, it would rock :)

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Easy Web Environment to post pupils Python Creations
by Philip Bagge April 2, 2014

April 2, 2014

Dear Colleagues, My Y6 pupils (10-11 year olds) have been creating some simple text based linear adventures using Python. Does anyone know of a way we can play their adventures online? They are not very complicated. You can see the planning here. https://sites.google.com/site/pythoncodecouk/python-adventure Also as a new person to your forum does anyone know of an easy way to search you archives just in case someone has already answered this question. Thanks in advance for any help Phil Bagge -- Primary ICT Advanced Skills Teacher HCC Teacher & IT Manager http://code-it.co.uk

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Re: [Edu-sig] Use of "badges" to encourage learning
by Laura Creighton June 28, 2013

June 28, 2013

You have to be really careful with this. The overwhelming evidence is that, most of the time, rewarding people for good performance makes them perform poorly. see: http://www.youtube.com/watch?v=u6XAPnuFjJc If your badge system ends up as a reward system, then you will end up with the same problems. Laura

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Use of "badges" to encourage learning
by Andre Roberge June 28, 2013

June 28, 2013

There seems to be a trend on various websites to award users "badges" to keep track of progress. Other than the rationale that "everyone is doing it this days so it must serve a purpose", do any of the edu-sig readers have experience with using "badges" or similar tricks to encourage learning when it comes to programming beginners?

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[ANNC] pynguin-0.15 python turtle graphics application
by Lee Harr June 14, 2013

June 14, 2013

Pynguin is a python-based turtle graphics application. It combines an editor, interactive interpreter, and graphics display area. It is meant to be an easy environment for introducing some programming concepts to beginning programmers. http://pynguin.googlecode.com/ This release makes major changes to the editor to enable line numbers and other improvements. Pynguin is tested with Python 3.3.1 and PyQt 4.10 and now requires QsciScintilla (tested with version 2.7.1) Pynguin is released under GPLv3. Changes in pynguin-0.15: Major change! - Now REQUIRES QsciScintilla! - included with PyQt4 on windows - .deb should pull in dependency automatically - other systems may require manual intervention Important fixes - writes out all document pages every time when saving - some pages could have been lost when changing between single file method and file + directory method of saving files Other fixes - fixed arc() with pen up - fixed loading pages with mixed defs and top-level code Pynguin API - added pie option to arc - draws pie wedges instead of just arcs - arc(radius, extent, pie=True) - added underline() method - pynguin.underline() # start underline for write() - pynguin.underline(False) # stop underline Canvas UI - loads .pyn file specified on command line - added ability to double-click open .pyn documents - tested on Ubuntu Linux only - shows better error message when there is a problem loading a file - saves/restores main window geometry/location Integrated Editor - Replaced editor with QsciScintilla text widget - Line numbers available now Integrated Console - Replaced QTextEdit with QsciScintilla text widget Examples - added fraction example to demonstrate arc(..., pie=True) - also demonstrates underline()

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Reeborg's world
by Andre Roberge June 12, 2013

June 12, 2013

In the spirit of the original CP4E (Computer programming for everybody) that lead to the creation of edu-sig, but unfortunately not (yet) supporting Python, I am happy to announce the launch of Reeborg's World ( http://reeborg.ca) as the successor to RUR-PLE (http://code.google.com/p/rur-ple) but adapted for the web ... and designed to teach Javascript. Eventually (soon?) there will be a Python version (using either Brython or Skulpt). Compared with RUR-PLE (inspired by Guido van Robot, itself inspired by Karel the Robot) Pros: No installation required - available on the web Much more teaching material Test-Driven Learning: one can set up world with "goals" (end configuration) that are automatically tested Side and Top view of robot, based on user preference Syntax analysis (and feedback) performed by JSHint Often used user-defined functions (such as turn_right) can be saved by the user in their "Library" and loaded automatically Cons: No highlighting of current instruction being executed No graphical world builder (could be added with a fair bit of work) Only English lessons and interface (soon French will be added) Not Python (will be fixed! :-) Cheers, André P.S. Developers thrive on feedback and are always happy to implement features sought by users. ;-)

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Python MOOC (massive open online course)
by John Posner June 10, 2013

June 10, 2013

At the nytimes.com site, I came across a reference to this Python course in the comments to Thomas Friedman's latest column: http://blog.topfreeclasses.com/2012/12/an-introduction-to-interactive-pytho… Does anyone have any direct knowledge of this (or any other) Python MOOC? -John

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Re: [Edu-sig] FYI: Discrete Math class this year
by calcpage June 9, 2013

June 9, 2013

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more promoting of Python for STEM curricula
by Kirby Urner June 7, 2013

June 7, 2013

More promulgating of: 'Mathematics for the Digital Age and Programming in Python' on the math-teach / Math Forum list (hosted by Drexel U) where I'm a regular poster: http://mathforum.org/kb/thread.jspa?threadID=2574824 I put it on a "syllabus" of only three books, suggesting a kernel or core set of topics, all interconnecting: 1. MFTDA (good 'math through programming' text book) 2. Divided Spheres (a primer but with lots of history) 3. King of Infinite Space (biography) That's just to establish a 'terrain' or 'territory' in which further curriculum writing might be done and somewhat defines my own neighorhood as a curriculum writer, though I also do a lot more with cellular automata and cryptography. Kirby

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